This invention relates to crystalline 5R,6S,8R-1.beta.-methyl-2-(N,N-dimethyl carbamimidoylmethylthio)-6-(1-hydroxyethyl)-1-carbapen-2-em-3-carboxylic acid and a process for its preparation.
The antibiotic 5R,6S,8R-1.beta.-methyl-2-(N,N-dimethyl carbamimidoylmethylthio)-6-(1-hydroxyethyl)-1-carbapen-2-em-3-carboxylic acid (I) is disclosed in U.S. patent application Ser. No. 289,345 (filed Aug. 3, 1981), now abandoned, which is incorporated herein by reference to the extent that it discloses the preparation of amorphous I and its utility, whether amorphous or crystalline as an antibiotic: ##STR1## The crystalline form of I, which is disclosed and claim by this application is prepared from a lyophilized sample of I and is found to have unexpected stability in the solid state and unexpected, superior solubility in water.